The present invention pertains to a brake pedal mechanism for motor vehicles with a pedal block, which is fastened to the body of the motor vehicle and accommodates a mount for the pivot axis of a rotatably mounted actuating pedal provided with a pedal surface, wherein an actuating element for a brake power booster is articulated to the actuating pedal.
Various embodiments of brake pedal mechanisms of the above-described type of this class are installed in each motor vehicle. They are used to transmit the brake power applied by the driver of the vehicle during the braking operation by actuating the brake pedal to the main brake cylinder via the brake booster, where the brake power is converted into hydraulic or pneumatic energy. In the case of usual requirements imposed on the upper, free end of the actuating pedal facing away from the pedal surface, the actuating pedal is mounted rotatably, and the articulation point for the actuating element of the brake power booster is arranged between the pedal surface and the mount of the brake pedal. The power transmission by the actuating element from the actuating pedal to the brake power booster or to the main brake cylinder is subjected to pressure. The overall length of the brake system from the main brake cylinder to the actuating pedal is approx. 400 mm and thus extends far into the engine compartment of the motor vehicle, which is disadvantageous especially in the case of an accident. Various suggested solutions have been developed in the state of the art to prevent the actuating pedal from penetrating into the passenger compartment due to the rearward displacement of the main brake cylinder and the brake power booster in accident situations.
For example, the entire brake module of the motor vehicle may be supported by a crossbeam, which brings about the tilting of the brake cylinder or the kinking of the actuating plunger rod. These solutions are disclosed, e.g., in EP 0 836 968 as well as DE 196 06 690 and DE 196 06 427.
In addition, a solution was proposed according to which the brake pedal is prevented from penetrating into the foot area of the passenger compartment by the brake pedal being separated from its mount in an accident situation (DE 196 51 013) or by the brake power booster being arranged transversely rather than longitudinally, which is disclosed in DE 196 32 330.
The common feature of all the possible solutions is that they require additional components and fastening points, have a complicated design and require much space for their installation and thus make the entire brake system more expensive.
The object of the present invention is therefore to develop a brake pedal mechanism for motor vehicles in which it is ensured that the penetration of the brake pedal into the foot area of the passenger compartment is ruled out reliably and in which an inexpensive manufacture is at the same time possible while minimizing the space necessary for the installation.
This object is accomplished according to the present invention by the pivot axis mounted on the pedal block being arranged at the actuating pedal between the pedal surface and the articulation point of the actuating element for the brake power booster.
Due to this design embodiment, the actuating pedal is automatically pivoted away from the driver""s foot area during the movement of the main brake cylinder and of the brake power booster in the direction of the passenger compartment. A risk of injury or jamming for the extremities of the driver of the vehicle is thus reliably ruled out. Moreover, the central mounting of the actuating pedal makes it possible to shorten the length of the pedal because a larger pivot angle of the brake pedal is possible for the brake power booster as a consequence of the straight-line motion of the actuating element. Due to the central mounting of the actuating pedal, it is, of course, necessary to design the brake power booster and the main brake cylinder such that these no longer respond to pressure but to pull. Such a mode of operation can be obtained for the main brake cylinder, e.g., by rotating the two working pistons or by using a pulling piston rod which passes through a central hole of both pistons. The overall length of the piston arrangement may also be reduced.
Actuation by pulling instead of actuation by pressure has the great advantage in the case of the brake power booster. The latter can have a very simple design because actuation by pulling leads to a pulling together of the individual components of the brake power booster. Thus, it is no longer necessary to take special precautionary measures against the pulling apart of the brake power booster halves. The tension rods currently used in brake power boosters, whose use requires an additional design effort concerning the sealing of the pistons of the brake power booster against the tie rod, are eliminated for this reasons.